Effect Of Returning Spring Corn Stalks To Soil On Soil Micro-ecology And Yield Effect In Cold And Arid Regions

Northwest Hebei is the water source and the sand source of the Beijing-Tianjin-Hebei region.The wind erosion of the soil and the burning of straw in this area have an important impact on the air quality of the Beijing-Tianjin-Hebei region.Therefore,the protection of farmland in Northwest Hebei is a hot research topic.The low temperature and less rainfall in this area are not conducive to the decomposition of corn stalks,which is a difficult problem for spring corn stalks returning to the field for conservation tillage.There is an urgent need to develop protective tillage measures for returning spring corn stalks to the field in the cold and arid areas of northern Hebei Province.In this paper,three stalk returning methods that included large-ridge rotation sowing straw to field,straw returning to field plowing,and straw returning to field rotary tillagewere studied by analyzing the soil DOM components.soil microbial biomass,soil enzyme activity's temporal and spatial changes,and their yield effects.The micro-ecological influence law of straw returning to soil DOM transformation and microbial activity were reveale,and then the suitable way of returning spring corn stalk to the field in the cold and arid areas of Northwest Hebei were explored.The results showed:1.The DOM of farmland soil in the cold and arid areas of Northwest Hebei was dominated by humic acid-like(44.36%?49.85%),followed by fulvic-like acid(25.27%?29.17%).Straw returning promoted the transformation of soil DOM into small molecular organic matter,and the terrigenous characteristics were increased.The growth of corn promoted the degradation of soil DOM,enhanced the activity of biological sources,and weakened the degree of humification.The large-ridge rotation of straw returning to the field increased the proportion of soil DOM-like humic acid components.Straw returning to the field and plowing increased the proportion of soil DOM-like protein components.the proportion of soil DOM-like protein composition at the seedling stage Was increased by straw returning rotary tillage.2.The DOC content of farmland soil in the cold and arid areas of Northwest Hebei was from 2.22 mg.kg^-1to 7.31 mg.kg^-1,and returning straw to the field could increase the soil DOC content.Returning straw to the field increased the carboxyl,hydroxyl,carbonyl of the substituents on the aromatic ring of the soil DOM,and increased fat content.The proportion of organic matter such as lignin and quinine in the early stage of humification.The growth of corn increased the polar functional groups such as hydroxyl,carboxyl and carbonyl and other substituents on the DOM benzene ring structure in the soil.Rotary tillage was beneficial to increase the DOC content in the 0-20 cm soil layer,and straw return to the field and large-ridge rotation were beneficial to increase the aromaticity and humification degree of soil DOM.3.The soil MBC of spring corn field ranged fron 225.62 mg.kg^-1to397.47 mg.kg^-1.Returning straw to the field could increased the content of MBC,MBN and MBP in soil.The growth of maize promoted the increase of MBC and MBN content,and reduced the MBP content in soil.The large-ridge rotation method of returning straw to the field could significantly increase the content of MBC,MBN and MBP.Plowing reduced the MBN content in the 0-40 cm soil layer.Rotary tillage of straw returned to the field increased the MBP content of the plough layer soil.4.Soil invertase activity of spring corn farmland was from 8.20mg.g^-1.h^-1to 12.73 mg.g^-1.h^-1,and urease activity ranged from 13.09mg.g-1.h-1 to 17.30 mg.g^-1.h^-1.Returning straw to the field could increase the activities of soil invertase and urease,and the growth of spring corn promoted the activity of soil invertase and reduced the activity of urease.The large-ridge rotation sowing straw increased the activities of invertase and urease more than the other two methods.Returning straw to the field and plowing were beneficial to increase the soil enzyme activity in the20-40cm soil layer,straw returning to the fieldand rotary tillagewas beneficial to increase the soil enzyme activity in the 0-20cm soil layer.5.The yield and the thousand-grain weight of spring maize were increased by retuening straw to the field.MBC,MBP,sucrase activity and urease activity were extremely significantly positively correlated with spring corn yield.With the increase of corn yield,soil DOM biosources increased.With the increase of spring corn grain weight,MBN content decreased.The aroma of soil DOM decreased with the increase of spring corn grain weight,ear thickness,and ear length.Returning straw to the field in the cold and arid areas of Northwest Hebei could improve the soil micro-ecological environment and promote the conversion of soil nutrients.Returning straw to the field and plowing was beneficial to improve soil enzyme activity and soil fertility supply capacity,and ot promote soil nutrient conversion.However,the large-ridge rotation of straw returning to the field could increase the soil DOM content and microbial activity.Compared with the straw returning to the field,rotary tillage and plowing,the large-ridge rotation improved the stability of the soil DOM,and increased the yield of spring corn.